Engine: slightly more stress-testing of Receiver/Sender to reproduce the hang problem

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)

engine/remote_test.go

@@ -1,6 +1,7 @@
 package engine
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"github.com/dotcloud/docker/pkg/beam"
@@ -10,6 +11,7 @@ import (
 )
 
 func TestHelloWorld(t *testing.T) {
+	for i := 0; i < 10; i++ {
 		testRemote(t,
 
 			// Sender side
@@ -21,20 +23,38 @@ func TestHelloWorld(t *testing.T) {
 				if job.status != StatusOK {
 					t.Fatalf("#%v", job.StatusCode())
 				}
-			if out.String() != "hello world\n" {
-				t.Fatalf("%#v", out.String())
+				lines := bufio.NewScanner(out)
+				var i int
+				for lines.Scan() {
+					if lines.Text() != "hello world" {
+						t.Fatalf("%#v", lines.Text())
+					}
+					i++
+				}
+				if i != 1000 {
+					t.Fatalf("%#v", i)
 				}
 			},
 
 			// Receiver side
 			func(eng *Engine) {
 				eng.Register("echo", func(job *Job) Status {
+					// Simulate more output with a delay in the middle
+					for i := 0; i < 500; i++ {
 						fmt.Fprintf(job.Stdout, "%s\n", strings.Join(job.Args, " "))
+					}
+					time.Sleep(5 * time.Millisecond)
+					for i := 0; i < 500; i++ {
+						fmt.Fprintf(job.Stdout, "%s\n", strings.Join(job.Args, " "))
+					}
 					return StatusOK
 				})
 			},
 		)
 	}
+}
+
+// Helpers
 
 func testRemote(t *testing.T, senderSide, receiverSide func(*Engine)) {
 	sndConn, rcvConn, err := beam.USocketPair()